How Often Should You Change Your Transmission Fluid?

by David Eiranova
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Image by, courtesy of Hamed Saber

One aspect of car maintenance that often gets overlooked is replacement of the transmission fluid. Unlike changing your oil, changing the transmission fluid is not something that you have to do often. Depending on the model car that you have, you may not have to do it ever. These transmissions are indicated by the absence of a transmission dipstick. They are permanently sealed. But most transmissions require the fluid to be replaced on a periodic basis.


Transmission fluid can become contaminated, even without the transmission case ever opening. Metal that flakes off the gears, moisture that finds a way in and non-metallic, heat-resistant material from internal parts can all cause the transmission fluid to become contaminated.


Different manufacturers recommend different intervals for changing the transmission fluid. Check your owner's manual for the mileage recommended between transmission fluid maintenance. Generally speaking, automatic transmission fluid should be checked once a month to head off any problems before they develop (the condition of the fluid can be visually observed on the dipstick--contaminated fluid will look dirty and smell burned). Manual transmission fluid should be changed every 30,000 to 60,000 miles. If you change your transmission fluid yourself, be sure to use the correct type of fluid. There are different kinds.


Transmission fluid acts as a lubricant for the parts (gears, clutches, etc.) inside the transmission. This action prevents the transmission parts from developing excess heat. The transmission fluid also sometimes indirectly serves as part of the cooling system of the car if the vehicle is equipped with a transmission cooler.


Without transmission fluid, the operation of a car would not be possible, or at least not at the speed and efficiency to which we have become accustomed. Like so many other marvels of the modern world, transmission fluid serves a purpose that basically (and literally) keeps the wheels turning, yet goes unnoticed by many people.


Will your transmission fail if you don't change the fluid? Maybe not. But one thing is sure--a higher proportion of failed transmissions can be linked to contaminated fluid than to fluid that has been replaced. Transmission repairs are very costly, so it would seem to make a lot of sense to make sure that transmission fluid maintenance is done on a regular basis, even if it's only to pull up the dipstick and look at the condition of the fluid.

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